It took me a while to decide to upgrade the electronics on my car for a better cell connection. The Tesla is now 9 years old with 114,000 miles. But honestly the car is just fine and the items I am most interested in upgrading are quite small (CarPlay and a physically smaller car), or quite expensive (a giant battery giving around 300+ miles of range).
The 3G capability of the car was getting quite unreliable. About half the time it could not connect at all. At times having the traffic data on the screen is quite useful, and other times being able to find a new place on the map was helpful by name and not by address.
I was also experiencing another problem that I was informed was related to the old electronics. The car would take quite a while to wake up. Since installing the new electronics, the car wakeup time is not instantaneous but it feels faster than before. I never measured the amount of time, so this observation may be inaccurate.
AT&T has decided to completely discontinue the 3G network, and Tesla notified us that we needed to do the upgrade. I finally caved in and had the service done, which must occur at a service center. The final bill was $218.
TESLA OWNER 
Did you have it done? Was it successful. We took ours in for the same and then had a bunch of horrid things happen when it was in Tesla’s hands. The screen behind the steering wheel stopped working and we are up to about $6,000 or $7,000 to repair our 2012 Model S
Yes, mine was done and easy as I said in the post. Perhaps the dash screen was on the edge of breaking? I know my main screen died a few years ago and snuck in days before the warranty expired.